Torque transmitting member, combustion turbine engine including same, and method of use

Abstract

 A power transmission means (72) for connecting a rotatable shaft member (54) of a rotatable turbine member to a shaft portion (68) of an auxiliary device comprises an elongate tubular insert member (74) generally of wear resis­tant plastics material having a male spline outer surface and a female splined inner surface. The male splined surface is engageable with a corresponding female splined surface on shaft member (54), while the female splined inner surface is engageable with a corresponding male splined portion (70) on shaft (68). A washer (84), having radial projections (86) engageable with crenels (82) of the insert member, has a female threaded bore (88) for engagement with a tool for removing a worn insert member from shaft (54).

Description

[0001] The field of this invention is rotational torque transmitting members. More particularly, the present invention relates to torque transmitting spline couplings employed between rotational shafts to accommodate limited angular and radial misalignment therebetween while rota­tionally transmitting torque between the two shafts. Still more particularly, the present invention relates to a combustion turbine engine wherein an auxiliary device of the engine is coupled in torque transmitting relation with a shaft of the engine via such a torque transmitting member. Additionally, the present invention relates to a method of use of such a torque transmitting member as is described above.

[0002] Conventional turbine engines employ a tubular shaft member having a female spline defined therein coupling with a male spline shaft of auxiliary devices in order to drive auxiliary devices from the turbine engine or to receive torque from the auxiliary device, such as a starter motor. Unfortunately, such spline torque transmitting couplings are generally defined by a tubular steel shaft receiving a steel extension of an auxiliary component shaft. Consequently, if such shafts are misaligned either angu­larly, radially, or in both senses, the spline surfaces of the two shafts experience very rapid wear which eventually results in loss of function of the spline coupling between the turbine engine and its auxiliary component. A conven­tional solution to this problem has been to provide a polymer wear resisting and somewhat lubricious member either as an insert to the tubular shaft or as a sleeve upon the shaft of the auxiliary device. However, such wear resisting polymer intermediate members will nevertheless experience wear during their service life and require replacement. Such replacements of wear resisting polymer intermediates or of metallic shafts of turbine engines conventionally require considerable effort and result in extended downtime for the aircraft or other vehicle employing such a turbine engine. Accordingly, it is an object of the present invention to provide a torque transmitting member inter­coupling a pair of shafts such that angular and radial misalignment between the shafts is accommodated while resisting wear of the shafts themselves. An additional object of the present invention is to allow simplified and rapid replacement of such a torque transmitting member.

[0003] Accordingly the present invention provides a torque transmitting coupling of generally elongate tubular configuration having a right circular cylindrical shape in cross-section. The tubular member defines an outer surface having an axially extending male spline shape and an inner surface also defining an axially extending female spline shape. At one end of the torque transmitting member are defined a circumferentially spaced apart axially extending plurality of portions, each of substantially similar angular arc. The axially extending portions cooperatively define a similar plurality of crenels, each also of generally similar angular arc. An annular washer-like star member is received within the torque transmitting member at the one end and defines a plurality of circumferentially spaced apart radially outwardly extending arm portions. Each of the arm portions substantially matches the angular arc of the crenels of the torque transmitting member and is respec­tively received therein. The star member and the torque transmitting member cooperatively define axially disposed contacting thrust surfaces respectively within the crenels and upon the radially extending arm portions thereof.

[0004] Consequently, axial force applied to the starter member is transferred to the torque transmitting member. The star member also defines means for cooperatively coupling with a removal tool providing for movement of the star member and of the torque transmitting member together from a position of utilization.

[0005] In use of the torque transmitting member described above, a combustion turbine engine is provided with an elongate tubular shaft defining a female spline. The torque transmitting member is received within the tubular shaft with the male spline of the member engaging the female spline of the shaft. Consequently, the torque transmitting member provides a female spline within the tubular shaft. Such female spline may be engaged by an auxiliary device of the combustion turbine engine in order to transfer torque between the auxiliary device and the engine. The torque transmitting member is disposed within the tubular shaft with the star member thereof axially spaced from the opening of the tubular shaft. Consequently, a removal tool may be inserted into the shaft through the torque transmitting member to engage the star member. Withdrawal of the star member from the tubular shaft also causes withdrawal of the torque transmitting member therefrom. Consequently, a replacement torque transmitting member may be installed into the shaft after a worn similar member has been removed therefrom.

[0006] The present invention offers as advantages the ability to quickly and easily replace worn female spline surfaces of a combustion turbine engine. Such replacement of worn female spline surfaces may be accomplished without significant disassembly of the combustion turbine engine. Advantageously, such replacements may take place with the turbine engine installed on an aircraft or within another vehicle so that removal of the engine and excessive downtime for the vehicle is not required. It will be seen then that the present invention obviates the need for protracted downtimes of vehicles and of combustion turbine engines employed therein in order to facilitate replacement of worn female spline surfaces thereof.

Figure 1 provides a schematic representation of a combustion turbine engine having a gear train coupling a power output shaft of the turbine engine to a power absorb­ing device and to an auxiliary device of the engine.

Figure 2 is a somewhat schematic perspective view of a combustion turbine engine having a gear train disposed within a housing providing a mounting for torque transmit­ting coupling of an auxiliary device to the engine.

Figure 3 provides a fragmentary perspective view of a shaft member defining a portion of the gear train of the combustion turbine engine illustrated in Figure 2 and receiving a torque transmitting member according to the present invention.

Figure 4 depicts component parts of a torque transmitting member according to the present invention.

Figures 5-8 illustrate fragmentary views partially in cross-section of a combustion turbine engine including a torque transmitting member according to the present inven­tion and of tools employed to remove the component parts of the torque transmitting member illustrated in Figure 4, and to effect replacement of such components.

[0007] Figure 1 schematically depicts a combustion turbine engine (10) including a compressor (12) inducting ambient air (14) and delivering this air pressurized to a combustor (16). Within the combustor (16), fuel (18) is mixed with the pressurized air and burned to produce a flow of pressurized motive gases which are supplied to a turbine (20). The turbine (20) expands the pressurized gases to ambient pressure for discharge as is depicted by arrow (22) and rotationally applies torque to a shaft (24) driving the compressor (12). The shaft (24) also is drivingly connected with a pinion gear (26) of a gear train generally referenced with the numeral (28). The gear train (28) drives a power absorbing element (30) via a shaft (32). For example, the power absorbing element may be a propulsion propeller for an aircraft as is depicted by Figure 1. The gear train (28) also includes a gear member (34) which is drivingly connected with an auxiliary device (36) by a coupling shaft (38). By way of example only, the auxiliary device (36) may comprise an alternator for providing elec­trical power to the vehicle employing the engine (10). Alternatively, the auxiliary device (36) may comprise a starting apparatus for the combustion turbine engine (10).

[0008] Figure 2 somewhat schematically depicts a com­bustion turbine engine (10) having a housing (40). The housing (40) defines a mounting pad (42) upon a gear case portion thereof for receiving an auxiliary device (36) such as is depicted schematically in Figure 1. The mounting pad (42) includes an annular raised boss (44) from which extends a plurality of studs (46) for securing the auxiliary device (36) to the gear case of the combustion turbine engine. Within the boss (44) the mounting pad (42) also includes a bearing retainer member (48) defining an opening or aperture (50). Projecting through the aperture (50) of the bearing retainer (48) is an end portion (52) of a shaft member drivingly connected in the gear train (28) as is schematic­ally depicted by Figure 1.

[0009] Viewing now Figure 3, it will be seen that the shaft member (54) defines a pair of axially spaced apart bearing seat portions (56) and (58). The shaft member (54) is carried by a pair of axially spaced apart anti-friction bearings (60) and (62) which respectively engage the bearing seat portions (56) and (58). Intermediate of the bearing seats (56,58) and bearings (60,62), the shaft portion (54) defines a spur gear portion (34) which is also depicted schematically in Figure 1. The spur gear portion (34) is drivingly engaged by the gear train (28) housed within the gear case of housing (40) of the combustion turbine engine (10).

[0010] In order to drivingly couple the shaft (54) with an auxiliary device (36) as is schematically depicted in Figure 1, the shaft (54) defines an axially extending stepped bore (64) opening outwardly within the end portion (52) and centrally within the mounting boss (44) of the gear case, viewing Figures 3, 4, 5 and 8. In order to drivingly couple in torque transmitting relation with a coupling shaft (38) of the auxiliary device (36), the shaft member (54) defines an axially extending female spline surface (66) within the bore (64). Viewing Figure 3, it is seen that the auxiliary device (36) includes a shaft portion (68) having a male spline portion (70) at a terminal end thereof. The male spline portion (70) is received within the bore (64) but is not drivingly engageable with the spline surface (66) thereof.

[0011] Viewing now Figure 4, it will be seen that a torque transmitting assembly (72) is received within the bore (64) in driving relationship with the shaft member (54). This torque transmitting assembly receives therein the male spline portion (70) of the shaft (68) in torque transmitting driving relationship. The torque transmitting assembly (72) includes an elongate insert member (74) fabricated of wear resistant polymer material. By way of example only, the polymer material from which the insert member (74) is fabricated may be Torlon, a product of Amoco Chemicals Corp. The insert member (74) is elongate and generally of tubular configuration and defines on its radially outer surface (76) an axially extending male spline surface. Similarly, the insert member (74) defines an axially extending female spline surface (78) therewithin. The spline surfaces (76) and (78) extend continuously from one end of the insert member (74) to the other end thereof. At one end, the insert member (74) defines a circumferentially spaced apart plurality of axially extending portions (80). The axially extending portions (80) cooperate to define axially extend­ing crenels (82) therebetween.

[0012] An annular washer (84), also known as the star member or removal member, is received within the one end of the insert member (74) and defines a plurality of circum­ferentially spaced apart radially outwardly extending arm portions (86). The arm portions (86) are respectively received within the axially extending crenels (82) of the insert member (74). The radially outwardly directed end surfaces of the removal member (84) arm portions 86 collec­tively define an outer diameter which is less than that of the minor diameter defined by the male spline surface (76). However, the arm portions (86) extend radially outwardly approximately to the minor diameter of the male spline surface (76). Consequently, each of the radially outwardly extending arm portions (86) defines an axially disposed surface (86A) each engaging the insert member (74) within a respective one of the crenels (82). An axially extending through bore (88) of the removal member (84) defines a female thread extending therethrough. The removal member (84) is received within the one end of the insert member (74), and there is captively retained by a spiral snap ring retainer member (90). The retainer member (90) is received by a plurality of like circumferential notches (92) defined by each portion (80) of the insert member (74).

[0013] Viewing Figure 5, it will be seen that the torque transmitting assembly (72) is received entirely within the bore (64) of shaft member (54). The male spline surface (76) of insert member (74) frictionally engages the female spline surface (66) of bore (64) within shaft member (54). In other words, the insert member (74) is an interference fit in bore (64) with the splines (66) and (76) drivingly engaging in torque transmitting relation. Thus, it is the insert member (74) of assembly (72) which defines a female spline surface (78) for driving engagement with the male spline portion (70) of shaft (68) of auxiliary device (36), viewing Figures 1 and 3.

[0014] In order to remove the torque transmitting assem­bly (72) from bore (64) of the shaft (54), a removal tool (94) is provided, viewing Figures 5 and 6. The tool (94) includes an elongate cup-like portion (96) which is receiv­able over the shaft end portion (52) to engage the inner race of bearing (62). The portion (96) defines a reduced diameter bore (98) through which passes an elongate threaded shank (100). The shank (100) defines a driving part (102) and carries a nut (104) capturing a thrust washer (106) between the latter and cup portion (96).

[0015] In use of the tool (94) to remove a worn assembly (72) from an engine (10), the shank (100) is threadably engaged with removal number (84) of the assembly, and the cup portion abuts bearing (62). Thereafter, drive part (102) is employed to prevent rotation of shaft (100) and the transmission of torque to portion (84) and assembly (72), while the nut (104) is threaded along the shank (100) against washer (106). As a result, the tool (94) applies a straight axial tractive force to the assembly (72) without the application of torque which might make withdrawal more difficult. The assembly (72) is drawn from the bore (64) of shaft (54) and into the cup-like portion (96) of tool (94).

[0016] In order to install a new torque transmitting assembly (72) into the bore (64) of shaft (54), an installa­tion tool (108) is provided, viewing Figures 7 and 8. The tool (108) includes an elongate threaded shank (110) of a size smaller than the shank (100) of tool (94). Consequently, the shank (110) may pass through the bore (88) of removal member (84) to threadably engage a blind threaded bore (112) defined at the inner end of bore (64) by shaft member (54). The shank (110) includes a drive part (114) by which it may be gripped for threading into engagement with bore (112), and which may be used to prevent rotation of the shank (110) in later use of the tool (108) as will be explained.

[0017] Slidably received upon the shank (110) of tool (108) is a guide assembly (116). The assembly (116) defines a stepped outer surface (118) providing a cylindrical portion (120) of approximately the same diameter as the inner diameter of insert member (74). That is, portion (120) is only slightly smaller than the minor diameter of spline surface (78) of the insert member (74). The portion (120) cooperates with an enlarged diameter portion (122) to define a shoulder (124). Viewing Figure 8, it is seen that assembly (72) is receivable upon guide assembly (116) with shoulder (124) in engagement with an end of insert member (74). The portion (120) extends within the insert member (74), but does not contact the removal member (84).

[0018] The assembly (116) includes an inner sleeve part (126) relatively rotatable both on shank (110) and within assembly (116), and defining a radially outwardly extending flange (128). A pocket (130) within assembly (116) receives a ball thrust bearing (132), while a nut (134) threadably engaged with shank (110) is also engageable with the flange (128). In use of the tool (108), the fresh torque trans­mitting assembly (72) is received on the guide assembly (116). Thereafter, shank (110) is inserted into bore (64) of shaft (54), with drive part (114) being used first to threadably engage shank (110) with bore (112), and then to prevent further relative rotation of the shank (110). Finally, the nut (134) is threaded along shank (110) to force assembly (72) into bore (64) without applying any torque thereto which would make installation more difficult. Removal of the tool (108) leaves the fresh torque trans­mitting assembly installed in the shaft (54) of engine (10).

[0019] While our invention has been depicted and described with reference to one particular type of turbine engine and one particularly preferred embodiment of the invention, such reference is not intended to imply a limitation on the invention, and no such limitation is to be inferred. To those skilled in the pertinent art many modifications to and adaptations of the invention will no doubt occur.

Claims

1. Power transmission means (72) for connecting a rotatable shaft member (54) of a rotatable turbine member (20) adapted for extracting mechanical power from a flow of motive fluid, with a shaft portion (68) of an auxiliary device (34); said shaft member (54) including an end portion (52) opening outwardly of a housing (40) of a combustion turbine engine through an aperture (50) defined by the housing, characterized in that said end portion (52) defines an axially extending stepped bore (64) with an axially extending female spline surface (66) at an outer larger-­diameter portion of said stepped bore, and a female thread at an inner smaller-diameter portion (112) of said stepped bore; and in that said power transmission means (72) comprises an elongate tubular insert member (74) having a crenelated end portion (80, 82), a male spline surface on its radially outer surface (76), said male spline surface being interferingly engageable in torque transmitting relation with said female spline surface (66), said insert member having a respective female spline surface (78) on a radially inner surface, said female spline surface (78) being engageable with a correspond­ing male spline surface (70) on said shaft portion (68); an annular washer member (84) defining a female-threaded through bore (88) of inner diameter larger than the major diameter of said female thread of said shaft member, said washer member (84) being received within said tubular insert member (74) at said crenelated end portion (80, 82) and defining a plurality of radially outwardly extending portions (86) each terminat­ing in a radially outer surface, said radially outwardly extending portions (86) being received into the crenels (82) of said crenelated end portion and cooperatively defining an outer diameter receivable into said outer portion of said stepped bore (64), said insert member (74) and said portions (86) of said washer member (84) defining cooperating axially disposed engagement surfaces for transferring axial force to said insert member, and means (90) for retaining said washer member within said crenelated end portion of said insert member.

2. An installation tool (108) for inserting a transmission means (72) according to claim 1 into said rotatable shaft member (54), said installation tool (108) being engageable with said female thread of said inner portion (112) and an outer end surface of said insert member (74) opposite said inner end portion thereof for urging said insert member (74) into said outer larger diameter bore portion, to cause said male spline surface of said insert member to interferingly interengage with said female spline surface (66) characterized in that said tool includes an elongate shank (110) threadably engageable with said female thread of said shaft portion (112), and an annular guide member (116) slidably carried upon said elongate shank and having a stepped outer diameter (118), a smaller diameter section (120) of said guide member being slidably received within said insert member in supporting relationship there­with, and a larger diameter portion (122) cooperating with said smaller diameter portion (120) to define a shoulder (124) disposed toward said shaft portion, said shoulder engaging said outer end surface of said insert member (74), and means (134) for urging said guide member along said shank (110) toward said shaft (54).

3. An installation tool according to claim 2 characterized in that said means for urging said guide member along said shank comprises a nut member (134) threadably engaging said shank and engageable with said guide member in axial force-transmitting relation.

4. A removal tool (94) for removing a transmission means (72) according to claim 1 from said shaft member (54), said removal tool means being engageable with said female thread of said annular washer member (84) and said shaft member (54), characterized in that said tool (94) includes an elongate shank (100) threadably engaging said annular washer member (84), and an elongate annular cup-like member (96) slidably received upon said shank, said cup-like member (96) at an open end thereof engaging in force-transmitting rela­tion with said shaft member (54), and means for drawing said shank (100) through said annular cup-like member to withdraw said insert member (74) from said shaft portion (54) and into said cup-like member

5 A removal tool according to claim 4 character­ized in that said means for drawing comprises a nut member (104) threadably engaging said shank and bearing upon said cup-like member.

Drawing